Method to detect angle sensor performance degradation through dither monitoring

ABSTRACT

A method for detecting angle sensor performance degradation in a flow angle measurement device in moving platform, such as aircraft and watercraft, as well as stationary platforms. Sensor dither in a flow angle measurement device is used to detect operational performance degradation of the sensor as a result of dynamic response changes caused by damaged or degraded mechanical components.

FIELD OF THE INVENTION

The present invention is directed to a method for detecting angle sensorperformance degradation in a flow angle measurement device in movingvehicular platforms, as well as stationary platforms. More particularly,the present invention is directed to a computer system and method thatutilizes movement of sensor dither in a flow angle measurement device todetect operational performance degradation as a result of dynamicresponse changes caused by damaged or degraded mechanical components ofthe sensor.

BACKGROUND OF THE INVENTION

Angle flow measurement devices, such as aircraft angle of attack andangle of sideslip measurement devices, are subject to degradation anddamage resulting from a variety of sources, such as foreign objectdamage (“FOD”), internal electrical arcing provided by a lightingstrike, environmental moisture effects, or incursion of foreign matter.These events, if undetected, can affect both the static and dynamicangular measurement accuracy of these devices.

Traditionally, these errors must be detected by manual inspection of thesensor or by comparison of the sensor to other sensors installed on theplatform. In some platform applications, a major limitation of theexisting method is that manual inspections can only be performed whenthe platform is on the ground, or otherwise not in use, and is performedonly after a concern is identified by some other means. A sensorcross-comparison method, which might be used in operation, is usuallyable to detect only gross inaccuracies and may be susceptible to commonmode issues. The present invention addresses these limitations byproviding a means to detect degradation and damage within the device,while in use and on a regular basis, without the reliance on externalmonitoring.

SUMMARY OF THE INVENTION

In order to detect degradation and damage to angle flow measurementdevices as discussed above, the present invention is directed to acomputer system and method that utilizes the continuous movement ofsensor dither in a flow angle measurement device to detect operationalperformance degradation due to the dynamic response change of damaged ordegraded mechanical components.

In accordance with an illustrated embodiment, the invention provides ameans to detect damage and/or degradation within a flow anglemeasurement sensor during normal operation, automatically and on aregular basis, without reliance on external monitoring. The presentinvention preferably utilizes real-time analysis of the dynamiccharacteristics of the angle sensor to detect damage and/or degradation.In contrast, the technology of the prior art relies on manual inspectionor comparison to similar sensors installed on the platform.

In accordance with an illustrated embodiment, and in one aspect, theinvention relates to a method for detecting angle sensor performancedegradation in a flow angle measurement device including the steps ofinputting current platform data and determining if the current platformdata is within predetermined limits. If the current platform data iswithin predetermined limits, then a current vane angle on the anglesensor is detected and stored in a Vane Angle Array. Next, averages ofthe current platform environment are calculated, which preferablyincludes airspeed, altitude and temperature, to obtain a Velocity DataArray. A next step includes looking up corresponding values for AngleFilter Coefficients and a Dither Threshold based on the calculatedaverages of the current platform data and using Angle FilterCoefficients to filter the Vane Angle Array to calculate a Dither Array.Afterwards, a noise level value of the Dither Array is calculatedwherein the noise level value is preferably a characteristic of vaneoutput dither amplitude and frequency. A determination is then performedas to if the current vane operation exceeds the Dither Threshold basedon the calculated noise level of the Dither Array. A fail output is thenindicated if it is determined that the current vane operation exceedsthe Dither Threshold or a pass output is indicated if it is determinedthat the current vane operation does not exceed the Dither Threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention can be understood withreference to the following detailed description of an illustrativeembodiment of the present invention taken together in conjunction withthe accompanying drawings in which:

FIG. 1 is a block diagram of a computer system that can be used withcertain embodiments of the invention;

FIG. 2 is a top plan view of an aircraft nose showing the location ofangle flow sensors installed on the sides of the fuselage in anillustrative embodiment of the invention;

FIG. 3 is a side plan view of an aircraft nose showing the location ofan angle flow sensor installed on the left side of the fuselage in anillustrative embodiment of the invention;

FIG. 4 is a vortex shedding diagram showing a top view of an angle flowsensor and airflow directions of the free incoming air stream and thevortex components during shedding in an illustrative embodiment of theinvention; and

FIG. 5 is a flow chart depicting steps included in the computer methodof the present invention for performing angular performance degradationdetection.

WRITTEN DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION

The present invention is now described more fully with reference to theaccompanying drawings, in which an illustrated embodiment of theinvention is shown. The invention is not limited in any way to theillustrated embodiment as the illustrated embodiment described below ismerely exemplary of the invention, which can be embodied in variousforms, as appreciated by one skilled in the art. Therefore, it is to beunderstood that any structural and functional details disclosed hereinare not to be interpreted as limiting the invention, but rather areprovided as a representative embodiment for teaching one skilled in theart one or more ways to implement the invention. Furthermore, the termsand phrases used herein are not intended to be limiting, but rather areto provide an understandable description of the invention. Additionallylike reference numerals are to be understood to refer to like elements.

It is to be appreciated that the embodiments of this invention asdiscussed below may be incorporated as a software algorithm, program orcode residing in firmware and/or on computer useable medium (includingsoftware modules and browser plug-ins) having control logic for enablingexecution on a computer system having a computer processor. Such acomputer system typically includes memory storage configured to provideoutput from execution of the computer algorithm or program. It is alsoto be understood and appreciated the computer system may be located on avehicle (e.g., an aircraft or watercraft) which has an angle sensor(e.g., an angle flow measurement device) which is the subject of theinvention for detecting angle sensor performance degradation throughdither monitoring. However, it is also to be understood and appreciatedthe aforesaid computer system may also be located external of theaforesaid vehicle.

An exemplary computer system is shown as a block diagram in FIG. 1depicting computer system 100. Although system 100 is represented hereinas a standalone system, it is not limited to such, but instead can becoupled to other computer systems via a network (not shown) or encompassother embodiments as mentioned below. System 100 preferably includes anexternal interface 105, a processor 110 (such as a digital dataprocessor), and a memory 115. Memory 115 is a memory for storing dataand instructions suitable for controlling the operation of processor110.

An implementation of memory 115 can include a random access memory(RAM), a hard drive and a read only memory (ROM), or any of thesecomponents. One of the components stored in memory 115 is a program 120.

Program 120 includes instructions for controlling processor 110. Program120 may be implemented as a single module or as a plurality of modulesthat operate in cooperation with one another. Program 120 iscontemplated as representing a software embodiment of the method 200described herein below.

External interface 105 can include an input device, such as a keyboard,touch screen, tablet, API web services interface, speech recognitionsubsystem or external communications network, for enabling a user tocommunicate information and command selections to processor 110.External interface 105 may also include an output device such as adisplay or a printer. In the case of a touch screen, the input andoutput functions are provided by the same structure. A cursor controlsuch as a mouse, track-ball, or joy stick, allows the user to manipulatea cursor on the display for communicating additional information andcommand selections to processor 110. In contemplated alternativeembodiments of the present invention, the program 120 can executeentirely without user input or other commands based on programmatic orautomated access to a data signal flow through other systems that may ormay not require a user interface for other reasons.

While program 120 is indicated as already loaded into memory 115, it maybe configured on a storage media 125 for subsequent loading into memory115. Storage media 125 can be any conventional storage media such as amagnetic tape, an optical storage media, a compact disc, a floppy disc,a silicon based memory storage device or the like. Alternatively,storage media 125 can be a random access memory, or other type ofelectronic storage, located on a remote storage system, such as a serverthat delivers the program 120 for installation and launch on a userdevice.

The method 500 described herein has been indicated in connection with aflow diagram depicted in FIG. 5 for facilitating a general descriptionof the principal processes of an illustrated embodiment of theinvention; however, certain blocks can be invoked in an arbitrary order,such as when the events drive the program flow such as in anobject-oriented program. Accordingly, the flow diagram is to beunderstood as an example flow and that the blocks can be invoked in adifferent order than as illustrated.

FIG. 1 is intended to provide a brief, general description of anillustrative and/or suitable exemplary environment in which embodimentsof the below described present invention may be implemented. FIG. 1 isan example of a suitable environment and is not intended to suggest anylimitation as to the structure, scope of use, or functionality of anembodiment of the present invention. A particular environment should notbe interpreted as having any dependency or requirement relating to anyone or combination of components illustrated in an exemplary operatingenvironment. For example, in certain instances, one or more elements ofan environment may be deemed not necessary and omitted. In otherinstances, one or more other elements may be deemed necessary and added.

In the description that follows, certain embodiments may be describedwith reference to acts and symbolic representations of operations thatare performed by one or more computing devices, such as the computingsystem environment 100 of FIG. 1. As such, it will be understood thatsuch acts and operations, which are at times referred to as beingcomputer-executed, include the manipulation by the processor of thecomputer of electrical signals representing data in a structured form.This manipulation transforms the data or maintains them at locations inthe memory system of the computer, which reconfigures or otherwisealters the operation of the computer in a manner understood by thoseskilled in the art. The data structures in which data is maintained arephysical locations of the memory that have particular properties definedby the format of the data. However, while an embodiment is beingdescribed in the foregoing context, it is not meant to be limiting asthose of skill in the art will appreciate that the acts and operationsdescribed hereinafter may also be implemented in hardware.

Embodiments may be described in a general context of computer-executableinstructions, such as program modules 120, being executed by a computersystem 100. Generally, program modules 120 include routines, programs,objects, components, data structures, etc., that perform particulartasks or implement particular abstract data types. An embodiment mayalso be practiced in a distributed computing environment where tasks areperformed by remote processing devices that are linked through acommunications network. In a distributed computing environment, programmodules 120 may be located in both local and remote computer storagemedia including memory storage devices.

With the computer system 100 being described above, and in accordancewith an illustrated embodiment, and with reference now to FIGS. 2-5, thepresent invention monitors the oscillation characteristics of an angularfluid flow measurement device 10. As best shown in FIGS. 2 and 3,angular fluid flow measurement device 10 is shown installed on eitherside of an aircraft nose 12. It is to be appreciated and understood, thepresent invention is not to be understood to be limited to such anangular fluid flow measurement device 10 but rather may encompass avariety of angle flow measurement devices for measuring parameters suchas an aircraft angle of attack, and/or may encompass an angle ofsideslip measurement device.

The above mentioned oscillations which are to be monitored by theinvention are commonly known as “dither”, which are caused by vortexshedding of the portion of the angle sensor 10 exposed to the flow, asshown in FIG. 4. With reference to FIG. 4, arrows 14 indicateundisturbed free air flow; the arrow 16 shows the direction ofoscillating motion caused by vortex shedding; and arrows 18 show aseries of vortices that have been shed from the vane, also known as a“Karman Vortex Street”. The dither is defined by the amplitude andfrequency of the oscillations, and these characteristics are repeatablefor specific operational conditions. By referencing the sensor dithercharacteristics the system and method of the present invention is ableto determine if the sensor 10 is operating within normal limits.

It is to be understood the aforesaid referenced dither characteristicphenomenon is dependent upon the specific operating conditions fordevice 10. As a result of this dependency, a computer program algorithmpreferably in the program module 120 of system 100 accepts the platformsupplied operating data from device 10 as an input and determines whatthe appropriate acceptance criteria should be. The acceptance criterialevels are based on the detected dither level within the time basedangle signal.

With reference now to FIG. 5, shown is a flow chart depicting computerimplemented method 500 illustrating the steps of a computer programalgorithm implemented in computer system 100 for detecting the angularflow degradation based on the vortex shedding caused by the dithering ofthe angle flow sensor 10 in accordance with an illustrated embodiment ofthe invention.

Starting at step 510, system 100 compares the current platform (e.g.aircraft) environment data (e.g. airspeed, altitude, temperature, angleof attack, roll rate, etc.) to predetermined and stored values (“TestEnvelope”) of these parameters to determine if performing a test fordetermining angle sensor performance degradation is necessary. Next, atstep 520, the system preferably performs a decision to either continuewith the detection algorithm (via program module 120) or to start over(step 510) based on the comparison made in step 510 in the event theplatform data is not within the predetermined test envelope. Thus, inthe event the decision in step 520 is determined a “no”, then processflows to step 530 in which data stored from a prior loop (step 510 to520), which data is no longer valid, is caused to be purged from system100.

However, if the system determination in step 520 is a “yes”, thenprocess flows to step 540 in which the platform data referenced in step510 is stored within an appropriate set of arrays (e.g, the currentplatform data is stored in the Platform Data Array and the current VaneAngle is stored in the Vane Angle Array, preferably in memory of system100). It is to be understood and appreciated the Vane Angle Array ispreferably a time series of detected vane angle values whereby when asufficient number of data points are collected, the Vane Angle Array isconsidered full.

Next, process flows to step 550 in which system 100 determines if enoughdata is available to perform the evaluation of performance degradation.If “no”, meaning the dataset is not complete, then the process of system100 returns to Start to collect more data from preferably device 10. Andif “yes”, meaning the dataset for the Vane Angle Array is full andcomplete, process flows to step 560 in which system 100 calculates theaverages of the current platform environment, the Velocity Data Array,based on inputted time series values of airspeed, altitude andtemperature.

After the calculation of step 560 is performed by system 100, processflows to step 570 wherein based on the calculations determined in step560, the process of system 100 performs a lookup of the correspondingvalues for the Angle Filter Coefficients and the Dither Threshold,preferably in a lookup table or similar component in system 100. It isto be understood and appreciated the Dither Threshold is thecharacterized noise level which determines if a vane is operatingnormally or abnormally whereby levels beyond the Dither Threshold areconsidered to be abnormal. It is further to be understood andappreciated that instead of looking up corresponding values for theAngle Filter Coefficients, a fixed filter, or similar means may be used.

Process in system 100 then proceeds to step 580 wherein based on theAngle Filter Coefficients determined in step 570, a selectable band passfilter is applied to the Vane Angle Array to calculate a Dither Arrayusing Angle Filter Coefficients to filter the Vane Angle Array. Processthen flows to the step 590 in which system 100 calculates the noiselevel value of the Dither Array. It is to be understood and appreciatedthe noise level value is a characteristic of the vane output ditheramplitude and frequency.

Process then flows to step 592 in which system 100 determines if thecurrent vane operation, as measured by noise level (the dither levelvalue), is beyond the dither threshold using the Dither Threshold asdetermined in step 570. If “yes” then system 100 reports a failingoutput (step 594) which sets the Performance Degradation Monitor BIT tofail and preferably all data is then cleared and the aforesaid processreturns to Start. And if “no” (the current vane operation, as measuredby noise level (the dither level value) is not beyond the ditherthreshold) then system 100 reports a passing output (step 596) whichsets the Performance Degradation Monitor BIT to a Pass condition andpreferably data is then cleared and the aforesaid process returns toStart.

It is to be appreciated some of the advantages provided by the abovedescribed computer system and method of the invention include providingincreased safety for the vehicle reliant upon a fluid flow angularmeasurement device due at least to a lower probability of undetectedlatent failure in such a fluid flow angular measurement device. Furthera margin of increased safety for the aforesaid vehicle is also provideddue to in operation fault detection rather than relying on nonoperational periods for assessment. Additionally, reduced maintenancecosts are provided by obviating the need for a physical inspection bymaintenance personnel after vehicle operation in potential damageinducing environments, such as convective weather, and also due to theneed for fewer device removals and returns for devices having noperformance degradation. It is also to be appreciated and understood theinvention described in accordance with at least the illustratedembodiment may be employed in conjunction as a component of any freelymoving device on a vehicle including devices used to detect angular flowof fluids other than air.

As used herein, the term “process” is meant to be synonymous with anycode or program that can be in a processor of a host computer (e.g.,system 100), regardless of whether the implementation is in hardware,firmware or as a software computer product available on a disc, a memorystorage device, or for download from a remote machine. The embodimentsdescribed herein include such software to implement the equations,relationships and algorithms described above. One skilled in the artwill appreciate further features and advantages of the invention basedon the above-described embodiments. Accordingly, the invention is not tobe limited by what has been particularly shown and described, except asindicated by the appended claims. All publications and references citedherein are expressly incorporated herein by reference in their entirety.

Optional embodiments of the present invention may also be said tobroadly consist in the parts, elements and features referred to orindicated herein, individually or collectively, in any or allcombinations of two or more of the parts, elements or features, andwherein specific integers are mentioned herein which have knownequivalents in the art to which the invention relates, such knownequivalents are deemed to be incorporated herein as if individually setforth. Although illustrated embodiments of the present invention hasbeen described, it should be understood that various changes,substitutions, and alterations can be made by one of ordinary skill inthe art without departing from the scope of the present invention.

Those skilled in the art will readily recognize additional numerousadaptations and modifications which may be made to the present inventionwhich fall within the scope of the present invention as defined in theclaims. Moreover, it is intended that the scope of the present inventioninclude all foreseeable equivalents to the elements, structures andmethod steps described with reference to the drawings. Accordingly, theinvention is to be limited only by the scope of the claims and theseequivalents.

1. A method for detecting angle sensor performance degradation in a flowangle measurement device, comprising the steps of: inputting currentplatform data and determining if said current platform data is withinpredetermined limits; if current platform data is within predeterminedlimits, then a current vane angle on the angle sensor is detected andstored in a Vane Angle Array; calculating averages of the currentplatform environment, which include at least one of the followingparameters, airspeed, altitude or temperature, to obtain a Velocity DataArray, looking up corresponding values for Angle Filter Coefficients anda Dither Threshold based on the calculated averages of the currentplatform data and using Angle Filter Coefficients to filter the VaneAngle Array to calculate a Dither Array; calculating a noise level valueof the Dither Array, where the noise level value is a characteristic ofvane output dither amplitude and frequency; determining if the currentvane operation exceeds the Dither Threshold based on the calculatednoise level of the Dither Array; reporting a failing output if it isdetermined that the current vane operation exceeds the Dither Threshold;and reporting a passing output if it is determined that the current vaneoperation does not exceed the Dither Threshold.
 2. Acomputer-implemented method for detecting sensor performance degradationin a fluid flow angular measurement device, the method comprising thesteps of: monitoring oscillation characteristics of a fluid flowmeasurement device in a computer processor; and determining if the fluidflow measure device is physically damaged based upon referenced sensordither characteristics for the fluid flow measurement device asdetermined by a computer processor based upon the monitored oscillationcharacteristics of a fluid flow measurement device.
 3. Acomputer-implemented method for detecting sensor performance degradationin a fluid flow angular measurement device as recited in claim 2 whereinthe flow angular measurement device is coupled to and extends from anaircraft.
 4. A computer-implemented method for detecting sensorperformance degradation in a fluid flow angular measurement device asrecited in claim 3 wherein the flow angular measurement device isfunctional to determine an angle of fluid relative to the host platform.5. A computer-implemented method for detecting sensor performancedegradation in a fluid flow angular measurement device as recited inclaim 2 wherein the flow angular measurement device is coupled to andextends from a watercraft.
 6. A computer-implemented method fordetecting sensor performance degradation in a fluid flow angularmeasurement device as recited in claim 2 further including the step ofinputting real-time platform data from the fluid flow angularmeasurement device to the computer processor to determine if thereal-time platform data is within predetermined limits.
 7. Acomputer-implemented method for detecting sensor performance degradationin a fluid flow angular measurement device as recited in claim 6 furtherincluding the steps of detecting the real-time vane angle of the fluidflow angular measurement device and storing in memory the detectedreal-time vane angle.
 8. A computer-implemented method for detectingsensor performance degradation in a fluid flow angular measurementdevice as recited in claim 7 further including the step of calculatingaverages using the computer processor of the real-time platformenvironment for the fluid flow angular measurement device, which mayinclude airspeed, altitude and temperature, to obtain a velocity dataarray.
 9. A computer-implemented method for detecting sensor performancedegradation in a fluid flow angular measurement device as recited inclaim 8 further including the step of looking up in memory by thecomputer processor corresponding values for angle filter coefficientsand a dither threshold based on the calculated averages of the currentplatform data.
 10. A computer-implemented method for detecting sensorperformance degradation in a fluid flow angular measurement device asrecited in claim 9 further including the step of calculating a ditherarray by the computer processor using the angle filter coefficients tofilter a vane angle array of the fluid flow angular measurement devicedata.
 11. A computer-implemented method for detecting sensor performancedegradation in a fluid flow angular measurement device as recited inclaim 10 further including the step of calculating a noise level valuein the computer processor for the calculated dither array wherein thenoise level value is a characteristic of vane output dither amplitudeand frequency.
 12. A computer-implemented method for detecting sensorperformance degradation in a fluid flow angular measurement device asrecited in claim 11 further including the step of determining by thecomputer processor if the current angular measurement device vaneoperation, as it moves through the fluid flow, exceeds the ditherthreshold based on the calculated noise level of the dither array.
 13. Acomputer-implemented method for detecting sensor performance degradationin a fluid flow angular measurement device as recited in claim 12further including the step of indicating a damage condition for thefluid flow angular measurement device by the computer processor if thecomputer processor determines the current vane operation exceeds thedither threshold.
 14. A computer program product comprising a computeruseable medium having control logic stored therein for detecting sensorperformance degradation in a fluid flow angular measurement device, saidcontrol logic including comprising computer readable program means forcausing a computer to monitor oscillation characteristics of the fluidflow measurement device and determining if the fluid flow measurementdevice is physically damaged based upon referenced sensor dithercharacteristics for the fluid flow measurement device based upon themonitored oscillation characteristics of the fluid flow measurementdevice.
 15. A computer program product comprising a computer useablemedium having control logic stored therein for detecting sensorperformance degradation in a fluid flow angular measurement device asrecited in claim 14 wherein said control logic further causes saidcomputer readable program means to cause said computer to detect thereal-time vane angle of the fluid flow angular measurement device andstore in memory the detected real-time vane angle.
 16. A computerprogram product comprising a computer useable medium having controllogic stored therein for detecting sensor performance degradation in afluid flow angular measurement device as recited in claim 15 whereinsaid control logic further causes said computer readable program meansto calculate averages of the real-time platform environment for thefluid flow angular measurement device, which may include airspeed,altitude and temperature, to determine a velocity data array.
 17. Acomputer program product comprising a computer useable medium havingcontrol logic stored therein for detecting sensor performancedegradation in a fluid flow angular measurement device as recited inclaim 16 wherein said control logic further causes said computerreadable program means to look up in memory corresponding values forangle filter coefficients and a dither threshold based on the calculatedaverages of the current platform data.
 18. A computer program productcomprising a computer useable medium having control logic stored thereinfor detecting sensor performance degradation in a fluid flow angularmeasurement device as recited in claim 17 wherein said control logicfurther causes said computer readable program means to calculate adither array using the angle filter coefficients to filter a vane angleof the fluid flow angular measurement device using the calculated ditherarray for the fluid flow angular measurement device.
 19. A computerprogram product comprising a computer useable medium having controllogic stored therein for detecting sensor performance degradation in afluid flow angular measurement device as recited in claim 18 whereinsaid control logic further causes said computer readable program meansto determine if the current angular measurement device vane operation,as it moves through the fluid flow, exceeds the dither threshold basedon the calculated noise level of the dither array.
 20. A computerprogram product comprising a computer useable medium having controllogic stored therein for detecting sensor performance degradation in afluid flow angular measurement device as recited in claim 19 whereinsaid control logic further causes said computer readable program meansto indicate a damage condition for the fluid flow angular measurementdevice if it is determined the current vane operation exceeds the ditherthreshold.
 21. A computer program product comprising a computer useablemedium having control logic stored therein for detecting sensorperformance degradation in a fluid flow angular measurement device asrecited in claim 14 wherein the flow angular measurement device iscoupled to and extends from a host platform.
 22. A computer programproduct comprising a computer useable medium having control logic storedtherein for detecting sensor performance degradation in a fluid flowangular measurement device as recited in claim 14 wherein the hostplatform is an aircraft.
 23. A computer program product comprising acomputer useable medium having control logic stored therein fordetecting sensor performance degradation in a fluid flow angularmeasurement device as recited in claim 14 wherein the host platform is awatercraft.
 24. A computer program product comprising a computer useablemedium having control logic stored therein for detecting sensorperformance degradation in a fluid flow angular measurement device asrecited in claim 14 wherein the host platform is stationary.